In a manufacturing process for manufacturing semiconductor devices, liquid crystal panels, LEDs, solar cells or the like, a process gas is introduced into a process chamber which is being evacuated to perform various processes such as an etching process, a CVD process or the like. The process chamber for performing several processes such as an etching process, a CVD process or the like is evacuated by a vacuum pump. Further, the process chamber and exhaust apparatuses connected to the process chamber are cleaned periodically by supplying a cleaning gas thereto. Because exhaust gases such as the process gas, the cleaning gas or the like contain a silane-based gas (SiH4, TEOS or the like), a halogen-based gas (NF3, ClF3, SF6, CHF3 or the like), a PFC gas (CF4, C2F6 or the like) or the like, such exhaust gases have negative effects on the human body and on the global environment such as global warming. Therefore, it is not preferable that these exhaust gases are emitted to the atmosphere as they are. Accordingly, these exhaust gases are made harmless by the exhaust gas treatment apparatus provided at a downstream side of the vacuum pump, and the harmless exhaust gases are emitted to the atmosphere. Further, the exhaust gases discharged from the process chamber contain a gas such as SiH4 at high risk of combustion and explosion, and hence it has been customary to supply an N2 gas from a diluent N2 unit into the exhaust gases to dilute the exhaust gases. Further, in some cases, an exhaust from several chambers other than the process chamber such as a transfer chamber, a load lock chamber or the like of the manufacturing apparatus is connected to the vacuum pump and the exhaust gas treatment apparatus where an exhaust gas is treated.
In this manner, the exhaust system of a chamber in a semiconductor manufacturing apparatus, a liquid crystal panel manufacturing apparatus, an LED manufacturing apparatus or the like has the vacuum pump, the diluent N2 unit, the exhaust gas treatment apparatus and the like, and each apparatus of the exhaust system is operated by ON/OFF control based on signals from the manufacturing apparatus. For example, in the case where the semiconductor manufacturing apparatus is an LP-CVD apparatus, operational sequence in the manufacturing apparatus is as follows: wafer supply→vacuum drawing→temperature rise→film forming (material gas supply)→temperature fall→return to atmospheric pressure→wafer removal. The above operational sequence is repeated. Further, in order to remove solid matters which have adhered to the interior of the chamber, a cleaning gas (e.g., HF, ClF3, NF3 or the like) is supplied periodically into the chamber, and the chamber is evacuated. The vacuum pump is activated in response to a start signal for vacuum drawing from the manufacturing apparatus when the vacuum drawing step of the chamber is started, and the vacuum pump is stopped in response to a signal for return to atmospheric pressure from the manufacturing apparatus when the return step to atmospheric pressure of the chamber is started. Further, the exhaust gas treatment apparatus is activated in response to a start signal for film forming when the film forming step in the process chamber is started, and the exhaust gas treatment apparatus is operated during the film forming step. After the completion of the film forming step, the exhaust gas treatment apparatus is operated for a predetermined time and stopped. The diluent N2 unit also performs supply of the N2 gas and supply stop of the N2 gas in response to signals from the manufacturing apparatus. In this manner, each apparatus of the exhaust system is operated by ON/OFF control based on signals for starting and finishing of predetermined operation processes in the manufacturing apparatus.
The exhaust gas treatment apparatus is disclosed in Japanese laid-open patent publication No. 09-861, for example. The cleaning apparatus of pipes is disclosed in Japanese laid-open patent publication No. 2001-189277, for example.